import express, { Request, Response } from 'express';
import { McpServer } from '../../server/mcp.js';
import { StreamableHTTPServerTransport } from '../../server/streamableHttp.js';
import { z } from 'zod';
import { CallToolResult, GetPromptResult, ReadResourceResult } from '../../types.js';
import cors from 'cors';

const getServer = () => {
    // Create an MCP server with implementation details
    const server = new McpServer(
        {
            name: 'stateless-streamable-http-server',
            version: '1.0.0'
        },
        { capabilities: { logging: {} } }
    );

    // Register a simple prompt
    server.prompt(
        'greeting-template',
        'A simple greeting prompt template',
        {
            name: z.string().describe('Name to include in greeting')
        },
        async ({ name }): Promise<GetPromptResult> => {
            return {
                messages: [
                    {
                        role: 'user',
                        content: {
                            type: 'text',
                            text: `Please greet ${name} in a friendly manner.`
                        }
                    }
                ]
            };
        }
    );

    // Register a tool specifically for testing resumability
    server.tool(
        'start-notification-stream',
        'Starts sending periodic notifications for testing resumability',
        {
            interval: z.number().describe('Interval in milliseconds between notifications').default(100),
            count: z.number().describe('Number of notifications to send (0 for 100)').default(10)
        },
        async ({ interval, count }, extra): Promise<CallToolResult> => {
            const sleep = (ms: number) => new Promise(resolve => setTimeout(resolve, ms));
            let counter = 0;

            while (count === 0 || counter < count) {
                counter++;
                try {
                    await server.sendLoggingMessage(
                        {
                            level: 'info',
                            data: `Periodic notification #${counter} at ${new Date().toISOString()}`
                        },
                        extra.sessionId
                    );
                } catch (error) {
                    console.error('Error sending notification:', error);
                }
                // Wait for the specified interval
                await sleep(interval);
            }

            return {
                content: [
                    {
                        type: 'text',
                        text: `Started sending periodic notifications every ${interval}ms`
                    }
                ]
            };
        }
    );

    // Create a simple resource at a fixed URI
    server.resource(
        'greeting-resource',
        'https://example.com/greetings/default',
        { mimeType: 'text/plain' },
        async (): Promise<ReadResourceResult> => {
            return {
                contents: [
                    {
                        uri: 'https://example.com/greetings/default',
                        text: 'Hello, world!'
                    }
                ]
            };
        }
    );
    return server;
};

const app = express();
app.use(express.json());

// Configure CORS to expose Mcp-Session-Id header for browser-based clients
app.use(
    cors({
        origin: '*', // Allow all origins - adjust as needed for production
        exposedHeaders: ['Mcp-Session-Id']
    })
);

app.post('/mcp', async (req: Request, res: Response) => {
    const server = getServer();
    try {
        const transport: StreamableHTTPServerTransport = new StreamableHTTPServerTransport({
            sessionIdGenerator: undefined
        });
        await server.connect(transport);
        await transport.handleRequest(req, res, req.body);
        res.on('close', () => {
            console.log('Request closed');
            transport.close();
            server.close();
        });
    } catch (error) {
        console.error('Error handling MCP request:', error);
        if (!res.headersSent) {
            res.status(500).json({
                jsonrpc: '2.0',
                error: {
                    code: -32603,
                    message: 'Internal server error'
                },
                id: null
            });
        }
    }
});

app.get('/mcp', async (req: Request, res: Response) => {
    console.log('Received GET MCP request');
    res.writeHead(405).end(
        JSON.stringify({
            jsonrpc: '2.0',
            error: {
                code: -32000,
                message: 'Method not allowed.'
            },
            id: null
        })
    );
});

app.delete('/mcp', async (req: Request, res: Response) => {
    console.log('Received DELETE MCP request');
    res.writeHead(405).end(
        JSON.stringify({
            jsonrpc: '2.0',
            error: {
                code: -32000,
                message: 'Method not allowed.'
            },
            id: null
        })
    );
});

// Start the server
const PORT = 3000;
app.listen(PORT, error => {
    if (error) {
        console.error('Failed to start server:', error);
        process.exit(1);
    }
    console.log(`MCP Stateless Streamable HTTP Server listening on port ${PORT}`);
});

// Handle server shutdown
process.on('SIGINT', async () => {
    console.log('Shutting down server...');
    process.exit(0);
});
